Process of detinning.



J'OSEF WEBER, OF ESSEN-ON-THE-RUHR, GERMANY.

PROCESS OF DETINNING.

Ito- Drawing.

, which the following is an exact specification.

expense to the value of l have discovered that the'problem of de-' tinning commercially and on a large scale, by means of chlorin gas, has adifierent aspect from that which was presented in all prior processes of this kind with which I am familiar. Practically all of these processes have proceeded upon the assumption that, whatever thelparticular mode of procedure might be, it was essential to operate in such a manner that the temperature within the reaction chamber would-be so controlled as to keep it below the point at which the chlorin would substantially attack and combine with the iron, and that i'f the iron were substantially attacked the ratio of the total the products recovered would be prohibitive. Within this term total expense l of course include the cost of any auxiliary processes of purification of an impure product, etc. I have found,

' however, that in commercial detinning, it is practicable to keep well within the commerciallimit of this ratio, and at the same time efi'ect substantial economies, by a Wide departure from previous practice. The detinning of tin scrap by means of chlorin gas is an art that cannot be practised commercially except on a large scale. llf the ratio of expense to the value of the recovered products is exceeded, commercial detinning obviously becomes impracticable. There are many factors that enter into the determination of the value of the terms or this ratio, and particularly of its first term,

till

i. e. expense, which of course is usually the more variable and the more important. Among these are included the cost of chlorin, the time required for completing a run, the amount of chlorin that combines with the iron, etc., the expense of handling the aterials and of purification of the products of the reaction when this is necessary, etc, Some of these factors are controlled by conditions outside the detinni'ng process; but others are controlled wholly and mainly by the mode or practising the process. Among Specification of Letters Patent. IPaRbB HIbQQ (Emily, 27, 1914,

Application filed January 31, 1912. Serial No. 674,501.

the latter are the length of time required for completing a run, the percentage of chlorin that comblnes with the iron, the expense of purification, etc. A material saving effected in one of these factors may very greatly reduce the value of the first term of said ratio, and correspondingly increase the margin of profit inpractising the chlorin process of detinning. v I r In operating on a large scale, I have discovered that, contrary to all previous ex perience, ll believe, it is not essential in-the chlorin process to keep the temperature dur- 7 ing detinnin'g, down to a point so low that there will not be substantial attackupon the iron by the chlorin, and consequently substantially no conversion of chlorin, with ironfinto' ferric chlorid. l have discovered v that it is practical to depart from the lowtemperature chlorin process of detinning heretofore practised, to carry on commercial chlorin detinning operations at a temperature considerably above that at which the iron of the scrap is attacked While at the same time dissipating rapidly the heat gen: erated by the reaction, and to permit a" considerable percentage of the chlorin intro- -.duced into the reaction chamber te combine with the iron and form ferric chlorid-and that this may be done -while keeping the ratio oi the total expense to the value of the products recovered well Within the aforesaid commercial limit. l have found that the losses due to the union or a considerable percentage of the chlorin with the iron of the scrap, etc., are offset by the gain due to the saving in time requirec for carrying out the In practice chlorin detinning process, etc. l have been able to keep within the prescrlbed ratio and operate with such speed as to cause approximately 20% of the chlorin to combine with the iron of the scrap. T he temperature should not be allowed to rise too high, however, at any point in the re action chamber, and in order that it may be equalized throughout the chamber, and kept within properlimits, ll make use in practice of the method of equalizing and reducing the temperature set forth in the application Ser. No. 328,793, filed jointly by Karl GrOlClschmidtiand myself on the 1st August, 1906.

lln carrying outmy present process, ll-pref erably make use of a detinning tank having a capacity of say 60 tons, which tank is filled with the-scrap, this scrap'being usually in the form of compact bundles. Into this detinning vessel, the chlorin gas, preferably in a dry state, is then introduced and reacts upon the tin of the scrap, either alone or in point. Iniorder to prevent an undue rise in temperature at a localized point or points in the tank, a thoroughv commingling of the particles of gas, etc., is continuously effected in some suitable manner, as for example, by

v impartinga" violent circulating or whirling motion-to these particles, and as a result of this an immediate equalization of the temperature in the apparatus is obtained and may be readily maintained. -The desired result may be accomplished by any suitable means, as, for example, by dividing the detinning apparatus into two or more chambers and causing the fluids to circulate in them, or bycontinuously passing and repassing said fluids through a single chamber; a pump or other suitable means being employed in either case.

As in the similar process described in the aforesaid application, maintaining the'fluids in the reaction chamber'or chambers in violent motion results in a rapid reduction of the temperature within the apparatus by the convection of the heat by the particles of fluid to the walls of the chamber or other points where the heat is readily dissipated,

this action being usually assisted by, circulatmg cold water continuously over the outside of the apparatus in a manner well under-- stood.) In the present case, however, "while the temperature is effectively equalized at allpoints in the apparatus, it is not reduced to the same extenta's in the process of the aforesaid application, but instead is permitted to remaln at a considerabl higher level,

that is to say, at apoint at whlch a considerable percentage of chlorin present will at tack and combine with the iron of the scrap and thus form ferric chlorin, as 'wellas stannic chlorid, these two products being subsequently separated and recovered, or purified 1n any suitable manner, it being understood,

of course, that even when the additional time and expense of the subse 'uent separation and purification of the pro nets of the reaction are added to the time required for completing a'run under this high temperature process, the saving due to the time gained in" the mam reaction more than ofi'sets the time lost in completing a run under the theoremcally more advantageous process of detmning at such a low temperature that the iron of the scrap is not attacked and no subsequent separation and purification of the products of the reaction is required.

. What I claim is:

ing tin and iron in a closed vessel, which consists in subjecting said material to the action of chlorin gas at a" temperature above that at which the'ironis attacked, and continuously effecting a thorough commingling of the particles ,of gas in the vessel.

2. A process of treating material containing tin and iron in a closed vessel, which consists in subjecting said material to the action of chlorin gas at a temperature above that at which the iron is attacked, and simultaneously dissipating a large portion of the heat generated in the vessel by the reaction.

3. A process of treating material containing tin and iron in a closed vessel, which consists in subjecting said material to the action of ch orin gas at a temperature above that at which the iron is attacked, and con tinuously circulating said gas in contact with a heat-absorbing medium to dissipatea large portion of the heat generated in the vessel by the reaction.

4. The process of detinnin bundles of compressed tin scrap in a close vessel-,'which consists in subjecting said bundles to the action of chlorin gas at a temperature above that at which the iron of the scrap is attacked, and simultaneously dissipating a large portion of the heat generated in the vessel by the reaction.

5. A process of treating-material 'containing tin and iron in a closed vessel, which consists in subjecting said material to the action of chlorin gas at a temperature above 1 that at which the iron iszattacked, and si multaneously equalizing the temperature substantially throughoutthe reaction vessel and dissipating a large percentage of the 6. A process of treating material containing tin and iron in a closed vessel, which consists in subjecting said material to'the action of chlorin as at a tem erature above that at which the iron is attac ed, and simultaneously efiectin a thorough commingling of the particles 0 gas in the vessel and dissipating a large percentage of the heat gen- I containa tinuously effecting a thorough commingling of the particles of, gas vin the vesse1,1 and purifying the'resulting products ofthe re;

action.- ,8. A process of treating material contain- 105 I heat generated in thexvessel by the reaction.

iio

ing tin and ironin a closed vessel, which consists in subjecting said material to the action of chlorin as at a temperature above that at which the IIOIl is attacked and simul= taneously dissipating .a large portion of the .1 niieyaoa heat generated in thevessel hy the reaction, and purifying the resulting products of the reaction.

9. The process of detinnin hundles of compressed tin scrap in a clos vessel, which conslsts in subjecting saifl bundles in the presence of an inert gas to the action oi chlorin gas at a temperature alcove that at Which the iron of the scrap is attacked, continuously efi'ectin a thorough coma:- gling of the particles ot chlorin gas and inert as in the vessel, and purifying the resulting point that the tin will he convert exl into stannic chloritl a someot the iron into ferric chloriol.

- 11. The process of treating material vcontaining tin and iron to produce liuidl a a mo chlorid anolferric cornl, Winch consists in subjecting the material to the action of 'chlorin containing gas at a temperat above that at which the iron is attacked and simultaneously dissipating a large portion of the reaction heat by rapid movement of the gas. I

- lln Witness whereof l have hereunto set my hand in the presence of two Wlt118SS8= JQSEJF [n s] Witnesses: v

Hrmnn Nnnnn 

